Timing of ore mineralization using ore mineralogy and U-Pb dating, Iron Oxide Copper Gold Sin Quyen deposit, North Vietnam

Abstract

As so ci ate Ed i tor: Jacek Szczepañski Mag ne tite, py rite, pyrrhotite, chal co py rite and sphalerite are the ma jor min er als iden ti fied in the de posit, while il men ite, marcasite, ten nan tite, cubanite, ar seno py rite, ga lena, al la nite, chevkinite, ap a tite, Bi-na tive, bis muthi nite, electrum, na tive gold, and tellurides are the mi nor ones in the Iron Ox ide Cop per Gold (IOCG) Sin Quyen de posit. The REEs are hosted mostly by al la nite, and the mi nor min er als by chevkinite, monazite, ap a tite and uraninite. Based on chem i cal anal y ses and Raman spec tros copy, two va ri et ies of al la nite have been doc u mented: (1) with lower to tal REE con tents of 13-19 wt.%, and (2) with higher con tents of 20-23 wt.%. Uraninite from cop per-iron mas sive ores is inhomogeneous in both op ti cal prop er ties and chem i cal com po si tion. The con cen tra tions of ura nium and to tal rare earth el e ment ox ides (REOs) in the paragenetically ear lier uraninite are 84.55-85.96% and 1.9-8.0% on av er age, re spec tively, whereas in paragenetically later uraninite, the U and SREE 2 O 3 con cen tra tions are 96.2-96.7% and 1.3-2.7% on av er age re spec tively. The tho rium con cen tra tion in both the early and late uraninites is very low (0.21-0.22% and 0.2 % on av er age). These are the high est REE con cen tra tions as compared with the known con cen tra tions of these el e ments in uraninite. Elec tron microprobe "chem i cal" dat ing of the uraninite yielded an age of 500 ±33 Ma (n = 35) for the paragenetically early uraninite, and an age of 73 ±15 Ma (n = 6) for the paragenetically later ones. The min er als of the older age, which is in ter preted as the pri mary ore min er al iza tion stage, cor respond in age with a range of de pos its along the East Gond wana mar gin. The mea sured d 34 S of sul phide min er als from-2.78 to +8.65‰ sug gests hy dro ther mal or i gin of fluid that was re spon si ble for trans por ta tion and crys tal li za tion.

Gospodarka Surowcami Mineralnymi - Mineral Resources Management

“…For sulphides occurring in the Sin Quyen IOCG deposit, the measured values of 34 δS are 8.65 ‰ and 8.27‰ for chalcopyrite and pyrrhotite, respectively (Pieczonka et al 2019). Therefore, ∆ ch py = 0.38‰.…”

“…In the study deposit, allanite is the major carrier mineral for REE; bastnäsite, apatite and monazite are scarce (Ta 1975;McLean 2001;Gas'kov et al 2012). Titanite, epidote and uraninite are also REE-bearing minerals (Pieczonka et al 2019).…”

“…Li and Zhou (Li and Zhou 2017) and Li et al (Li et al 2018) reported that REE are also contained in monazite-(Ce) and chevkinite-(Ce) in the study deposit, but with subordinate abundance. In the deposit, LREE dominate with 692 ppm on average (McLean 2001;Ishihara et al 2011;Pieczonka et al 2015Pieczonka et al , 2017, while the average content of the HREE is 9 ppm. Optical investigation shows fine differences between two populations of allanites.…”

Relationship Between Some Selected Major, Minor and Trace Elements in the Iocg Deposits (On the Example of the Unique Sin Quyen Deposit, Lao Cai Province, North Vietnam)

“…The second part predominates in the western, where the major minerals are magnetite, pyrite, chalcopyrite and pyrrhotite contributing from a few percent up to 50% of ore (McLean, 2001;Gas'kov et al, 2012). Due to the occurrence of the large fractures system, the oxidized zone is clearly observed in the upper part near 100 m of depth below the earth surface ( Ta (1975) According to Li et al (2017), in the deposit region there were four principal mineralization stages: (i) the paragenetic sequence including with the sodic alteration, which was happened in the Proterozoic epoch; (ii) the calcic-potassic alteration and associated Fe-REE-(U) mineralization lasted in the Neoproterozoic (841 to 836 Ma); (iii) Cu-Au mineralization, the third stage probable happened at 500 Ma (Pieczonka et al, 2015(Pieczonka et al, , 2019 and the fourth stage was connected with the metamorphism occurred at the 30 Ma and the sulfide-(quartz-carbonate) veins were mostly established. The mineralization of the Sin Quyen deposit basically falls within the age range of the Neoproterozoic igneous rocks (740 -860 Ma) (Li et al, 2017).…”

“…In the placer gold deposits in the East of Siberian Platform with increasing of Au fineness the Ag content is decreased and Cu has an increasing tendency (Nikiforova et al, 2018). Though the IOCG Sin Quyen deposit has been investigated by several scientists, but they have principally focused on the geological structure, ore crystallization ages and occurrence of the specific minerals (Ta, 1975;McLean, 2001;Ishihara et al, 2011;Gas'kov et al, 2012;Li and Zhou, 2018;Pieczonka et al, 2019). The correlation coefficients between some elements in IOCG Sin Quyen deposit were also estimated by Gas'kov et al (2012), but the correlations were not interpreted or very weakly considered.…”